Faunal Communities of the Field Stratum and Their Succession in Reserved Fields
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JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND Maataloustieteellinen Aikakauskirja Vol. 49:390-405, 1977 Faunal communities of the field stratum and their succession in reserved fields Heikki Hokkanen and Mikko Raatikainen University of Jyväskylä, Department of Biology Yliopistonkatu 9, 40100 Jyväskylä 10, Finland Abstract. The arthropod of the field stratum and small mammal fauna of 51 reserved fields were studied in Central Finland in 1974. In high summer the arthropod density the 2 which formed was on average 210 individuals/m , of Auchenorrhyncha 42 %, Hyme- noplera 18 %, Coleoptera 14 %, and others 26 %. Arthropods were more abundant in fields that had been reserved after leys than in fields after open cultivations. The abun- dance of most arthropod taxa increased as the time in reservation increased. However, the abundance of most pests of any significance decreased with years. Sorex araneus L. and Microtus agrestis L. formed almost 90 % of the small mammal fauna of the fields. Their abundance was on the average much less than in the Scots pine seed orchards nearby. The leafhopper faunas were divided into three communities. One appeared in young (Ist —3rd year) fields, and the other two in older (2nd —6th year) fields, one in dry and one in moist fields. The Apion fauna was divided into four communities. The dependence of the described arthropod communities on the vegetational communities of the fields was weak, although some relationships were observable. 1. Introduction To decrease the area under cultivation, the Field Reservation Act (216/ 1969) was enacted in 1969. By the end of 1974 about 8 % of the cultivated area in Finland had been reserved (Anon. 1975). Research on the flora and fauna of reserved fields was started in the University of Jyväskylä in 1973. Several papers have been published on the subject, e.g. Törmälä and Hokka- nen (1976), Törmälä and Raatikainen (1976), Hokkanen and Raatikainen (1977), Törmälä (1977). The purpose of this study is to identify the most important animal taxa and faunal communities of the field stratum, as well as their succession in reserved fields. Relatively little information about the fauna of reserved or abandoned fields in Finland is presented in the literature, the works of Gyllenberg (1969), Koponen (1972), Törmälä and Raatikainen (1976) and Törmälä (1977) are almost the only ones from Finland. Much more is known about the fauna of cultivated fields, although most works deal only with one distinct group of animals. E.g. Markkula and Myllymäki (1958), Raatikainen (1971), Huhta 390 and Raatikainen (1974), Laitinen and Raatikainen (1975), and Raatikainen and Vasarainen (1976) present information from Finland; similar studies have been made e.g. in Sweden (Jurisoo 1964) and Poland (Andrzejewska 1971, Kajak et al. 1971, Olechowicz 1971, etc). 2. Material and methods 2. 1. Study area The study area consisted of the following communes; Jyväskylä, the rural commune of Jyväskylä, Petäjävesi and Uurainen (about 62° N and 25° E) in Central Finland. 20 reserved farms were selected at random, and from each 2—3 homogenous fields again at random. Thus 51 fields were obtained, which were reserved as follows: 13 in 1969 (= 6th year fields), 5 in 1970, 6 in 1971, 11 in 1972, 10 in 1973 and 6 in 1974 (= Ist year fields). Further details about the fields and the study area are given in Hokkanen and Raatikainen (1977). 2. 2. Sampling Arthropods were sampled in early summer (4 11. VI 1974) with standard sweep-nets described by Heikinheimo and Raatikainen (1962). Four samples, 15 sweeps each, were taken from each field between 10 a.m. and 4 p.m. The samples were not taken if it was rainy or if there was a gale, or the vegetation was wet. The animals were killed with diethyl ether, stored in a dry place, and sorted later by hand according to species (the most numerous or otherwise important species) or group. In high summer (16—24. VII 1974) quantitative samples were taken with Burkard suction apparatus from a circular metal enclosure with an area of 0.10 m 2 placed on the ground. A suction time of 1.5 minutes was used. 4randomly located samples were taken from each field, they were treated in the same way as the sweep-net samples. The nomenclature of Auchenorrhyncha is according to Linnavuolri (1969), and that of the Apions according to Hansen (1965) The abundance of small mammals was studied with the small quadrat- method described by Myllymäki et ai. (1971). Trapping was conducted be- tween 21—26. VIII. 1974 so that one quadrat was located per field. The whole material consisted of the catch from 1224 trap-nights. The nomenclature of small mammals is according to Siivonen (1974). 2. 3. Treatment of data Faunal communities were differentiated by means of the modified Spren- sen’s quotient of similarity: E 2c QS = 100 x , where E (a + b) a= the amount of a species in sample 1 b = the amount of the same species in sample 2 c = the smaller of these two values (a and b) The following symbols for the levels of significance are used in all the tests p*< 0.05, p** < 0.01, p*** < 0.001. 391 3. Results 3. 1. Taxa, their occurrence and abundance 3. 1.1. Arthropods The 202 sweep-net samples which were taken, contained a total of 13 640 arthropod specimsns. Table 1 shows the number of individuals in the different arthropod taxa/60 sweeps, according to different age classes and previous use Table 1. Number of arthropods in sweep-net samples according to the age and previous use of the fields. I—6 = age as a reserved field in years, O = fields reserved after open cultivations, L = fields reserved after ley or pasture, n = number of samples. Number of individuals/60 sweeps All Taxon L L1 201L 345Q 2 Q 3 Q 4 Q 5 06 L 6 fjelds Araneida 2.5 22.3 14.9 12.0 23.7 21.5 11.5 12.3 16.0 20.0 25.3 17.0 - Phalangida - - 0.1 - 0.0 Ephemeroptera 0.6 0.3 0.2 0.5 2.0 0.3 Plecoptera - 0.8 0.1 - - - - - 0.1 Orthoptera 0.8 0.3 0.1 2.5 2.7 1.2 0.2 1.0 0.8 1.7 1.0 Thysanoptera 5.3 3.8 7.3 42.0 25.3 2.2 1.0 154.3 125.3 8.8 4.1 36.0 Homoptera Auchenorrhyncha .... 1.8 10.8 14.4 27.0 40.4 64.2 18.5 42.7 34.5 72.3 111.0 44.1 Balclutha punctata . 0.3 2.5 10.7 4.5 22.7 4.7 8.0 9.0 0.3 3.0 3 1 6.0 Diplocolenus abdo- minalis - 2.3 - 3.5 3.7 5.5 - 10.7 8.5 6.3 22.0 6.7 - Doliotettix pallens . 2.3 0.9 9.0 2.0 38.2 2.5 7.2 15.1 42.3 47.0 17.5 Javesella spp 1.0 - 0.3 3.0 1.3 2.0 2.5 4.2 0.3 1.8 3.4 1.9 Megadelphax sordi- dula - 3.0 0.7 5.5 4.4 4.5 3.5 6.8 9.1 4.8 28.2 7.5 Stiroma bicarinata . 0.5 - 1.0 6.2 0.2 10.8 3.9 2.2 Psyllina 5.5 2.5 6.1 4.8 39.3 3.8 1.5 3.8 4.0 3.5 3.3 6.2 Heteroptera 4.0 12.8 3.5 10.1 64.7 10.3 21.0 8.9 12.1 22.8 10.2 13.6 Coleoptera 5.6 19.0 17.7 29.3 68.0 67.8 28.0 33.5 137.3 74.5 45.6 46.5 Apion spp 0.3 3.5 3.0 3.5 5.0 2.7 1.0 5.7 1.5 9.8 5.4 3.9 - - Chaetocnema spp . 1.0 0.5 1.3 2.7 0.3 0.6 Longitarsus spp. ... 0.3 1.8 2.0 C. 3 1.2 0.3 0.6 - - - Phyllotreta spp. ... 1.0 1.0 0.9 0.3 1.5 1.8 0.3 0.6 Sitona spp 0.3 1.8 0.6 3.0 0.7 1.5 0.2 - 1.3 1.9 0.9 - - Galerucellatenella . 5.5 9.3 3.3 15.0 0.2 1.3 52.3 7.9 7.3 Polydrosus mollis .. - 2.0 2.3 12.0 3.7 50.2 - 7.7 128.0 1.8 8.1 19.7 Agriotes obscurus... 0.3 0.2 0.0 Corymbites incanus 1.4 0.3 0.2 C. pectinicornis .... 0.3 0.2 0.3 0.1 Dolopius margina- - - - tus 0.3 0.3 0.2 0.5 - - 0.1 Hymenoptera 3.0 14.0 12.1 26.3 100.0 37.7 16.5 61.5 31.0 59.0 28.7 34.3 Lepidoptera - 0.1 1.3 1.0 0.5 - 0.5 0.3 0.5 0.4 0.4 Diptera 30.3 54.0 39.7 45.8 83.3 72.5 152.0 154.2 39.8 58.0 35.0 65.6 Amaurosoma armil- latum - 0.3 0.6 1.8 - 0.5 1.5 22 1.0 1.3 0.6 0.9 A. flavipes 0.5 8.8 4.1 3.5 4.0 1.3 1.0 6.0 7.3 5.0 1.1 3.8 Insecta, larvae 0.5 0.8 1.1 4.8 5.0 2.3 5.0 1.7 2.5 4.3 2.1 2.4 n 16 16 28 15 12 23 8 24 16 16 28 202 392 Table 2.